1. "If it hadn’t been for Hollywood, I’d have fulfilled my other childhood dream — to be a zookeeper," declares Betty White. She gets her wish on Dec. 3, closing out Nat Geo's Big Cat Week with the special “Betty White Goes WILD!” in which the nonagenarian animal lover gets up close and personal with some feline friends at the Los Angeles and San Diego zoos.

2. Shelby the Swamp Man plays Santa, dispensing such finds as a snakeskin headband and gator-tooth necklace to his friends in a made-over forklift sleigh in the History special “A Very Shelby Christmas,” premiering on Dec. 3.

3. Nat Geo Wild celebrates the beauty, drama and challenges of existence on Earth in the special “One Life.” Filmed all over the world and culled from 10,000 hours of remarkable, breathtaking footage of animal behavior, it’s narrated by Daniel Craig and premieres on Dec. 8.

4. Discovery’s “Naked & Afraid Special,” in which two pairs of strangers face the challenges of the Panamanian rainforest — in the nude — premieres on Dec. 8. On Dec. 14, “Naked & Afraid Bares All” will reveal unseen moments from the series and catch up with participants. The programs are part of “Discovery Unwrapped,” a week’s worth of holiday premieres and specials.

5. Five thrill-seeking survivalists including a Green Beret, ex-Navy Seal, two survival instructors and a wilderness guide are captured and dropped one by one into an unforgivingly harsh environment and must make it back to civilization before the 100-hour clock runs out in the seven-part series “Dude, You’re Screwed,” premiering on Discovery Channel on Dec. 10.

6. Marina Chapman claims that when she was 5 years old, she was abducted and left to die in the Colombian jungle and survived by living with the capuchin monkeys that cared for her. Is it true? The mystery unfolds as Chapman returns to Colombia to seek answers in this Animal Planet special airing on Dec. 9.

7. Are zombies purely fiction, or could a disease epidemic really turn humans into monsters? On Dec. 10, the Nat Geo special “How to Survive the End of the World: Zombie Apocalypse” posits a worst-case scenario caused by a mutated rabies virus and the global implications of its spread.

8. “Bering Sea Gold” returns to Discovery for its third season on Dec. 13, following prospecting crews — including Nome’s first female dredge owner Emily Riedel — as they vie to mine a fortune in gold buried beneath the sea.

9. Although the Sea Shepherds lost their leader when Capt. Paul Watson was forced to step down in 2012, the whale-saving activists continue his mission in the two-hour “Whale Wars: A Commander Rises” special airing on Dec. 13 on Animal Planet.

10. Nat Geo’s “Ultimate Survival Alaska” returns on Dec. 15 for its second season, challenging four teams of adventurers to traverse 1,500 miles of forbiddingly hostile frozen Alaskan terrain. Memorable from season one, mountain guide Marty Raney and Iditarod champ Dallas Seavey are heading the Mountaineers and Endurance teams; their opponents are Team Military and Team Woodsmen, which includes the expedition’s only woman, lumberjack “Timber” Tina Scheer.

18. Although he’s the fictional creation of Sir Arthur Conan Doyle, super sleuth Sherlock Holmes has had real-life impact on criminology and forensic techniques, which the two-hour PBS special “How Sherlock Changed the World” illustrates. It premieres on Dec. 17, a month before Masterpiece’s “Sherlock,” starring Benedict Cumberbatch, returns for its third season on Jan. 19.

20. Nat Geo Wild’s three-part series “Mustang Millionaire” follows five wild horse trainers as they vie to turn untamed equines into show horses in four months, with $1 million prize at stake. It premieres on Dec. 14.